Einstein, Theodore L.We begin by reviewing theoretical machinery for deducing the strength of repulsions between steps from spatial correlations. There are some noteworthy advantages to studying step-step correlation functions rather than just the terrace width distribution function (i.e. correlations between adjacent steps). Highlights of this work are summarized. These ideas and traditional analyses of spatial and temporal correlations are applied to REM data for vicinal Si(111) above the sublimation temperature, but with a compensating flux, and find striking behavior for the apparent step repulsion strength. To distinguish the atomic-scale mechanisms of evaporation condensation and diffusion step-to-step, correlations of symmetric combinations of step displacements can be used. This idea is being applied to a chemically heterogeneous Si surface as well as the Si data. Using a Schrodinger equation approach, one can not only present a justification for the generalized continuum Wigner surmise but also contend with complicated step interactions more complicated than inverse square, as might occur due to step interactions mediated by surface states or for small step separations where contributions beyond the leading asymptotic term become important.Article